a demo is a stupid idea for all the reason explained above, they alredy had to dealy the game TWO times, and by a grand total of 8, EIGHT months,now. nd this, i think , only to mantain the standards they showed in the early trailers ( i hope to God ) we don't need any further weightload on them beofre release, i even given up on the notion of having the 16 dlc planned for launch after the first delayed release date that by logic sohuld have been implemented at launch in the new second dealyed launch, but not if will couse problems like i was told it would. so a demo? no.
on the other heand abenchmark tool would really awesome. not necessairly before release but if is implemented even after as an ingame option, like what we have in shadow of mordo for example it would be reaaally good and i hope it happens at some point